| Summary: | The stationarity of historical hydrological time series is a fundamental assumption
of water resources management. When this assumption proves valid, a time series is
regarded as a stochastic process with constant statistical parameters. Anthropogenic
activities may invalidate this assumption. Land use changes within a watershed may alter
hydrologic characteristics. On a more regional scale, increased levels of atmospheric
CO2 could potentially result in perturbations of climatic patterns. In addition, evidence of
cyclical patterns exists in historical climate records. Provided these changes are not
offsetting, they may manifest themselves as nonstationarities in the statistical parameters
of hydrologic time series.
The objective of this study was to investigate the assumption of stationarity in
long-term peak annual streamflow records across British Columbia. Twenty-five peak
annual streamflow records were grouped into five delineated regions. Nonparametric
statistical tests were applied to each streamflow series within the region. Each region
was then 'collapsed' into a single figure representing the test parameter for that region.
These parameters were tested for trends and jumps in location, dispersion and overall
distribution characteristics of each region. Finally, the regional results were contrasted
against various Monte Carlo simulations to evaluate the probability that the magnitude of
nonstationarity signified by each regional parameter could have resulted from random
climatic variation.
Evidence of drastic temporal decreases in mean peak annual floods suggested that
stationarity is not a valid assumption for gauging stations located in the designated "East"
region of British Columbia. A similar conclusion can be inferred for the region
designated as "Mid North," where all flood frequency distribution parameters exhibit
notable magnitudes of nonstationarity; Other regions showed inadequate evidence or do
not contain enough information to dismiss the assumption of stationarity. === Forestry, Faculty of === Graduate
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